X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/c3caa2face1cda7002eb58245ad75865bf437455..34e4f738bcba58e6d8c4cabbb0b3232a65b42a9d:/field.h

diff --git a/field.h b/field.h
index dd674c9..bf0428a 100644
--- a/field.h
+++ b/field.h
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: field.h,v 1.4 2004/03/21 22:52:06 mdw Exp $
+ * $Id: field.h,v 1.9 2004/04/01 12:50:09 mdw Exp $
  *
  * Definitions for field arithmetic
  *
@@ -30,6 +30,25 @@
 /*----- Revision history --------------------------------------------------* 
  *
  * $Log: field.h,v $
+ * Revision 1.9  2004/04/01 12:50:09  mdw
+ * Add cyclic group abstraction, with test code.  Separate off exponentation
+ * functions for better static linking.  Fix a buttload of bugs on the way.
+ * Generally ensure that negative exponents do inversion correctly.  Add
+ * table of standard prime-field subgroups.  (Binary field subgroups are
+ * currently unimplemented but easy to add if anyone ever finds a good one.)
+ *
+ * Revision 1.8  2004/03/27 17:54:11  mdw
+ * Standard curves and curve checking.
+ *
+ * Revision 1.7  2004/03/27 00:04:46  mdw
+ * Implement efficient reduction for pleasant-looking primes.
+ *
+ * Revision 1.6  2004/03/23 15:19:32  mdw
+ * Test elliptic curves more thoroughly.
+ *
+ * Revision 1.5  2004/03/23 12:08:26  mdw
+ * Random field-element selection.
+ *
  * Revision 1.4  2004/03/21 22:52:06  mdw
  * Merge and close elliptic curve branch.
  *
@@ -59,22 +78,45 @@
 
 /*----- Header files ------------------------------------------------------*/
 
+#ifndef CATACOMB_GRAND_H
+#  include "grand.h"
+#endif
+
 #ifndef CATACOMB_MP_H
 #  include "mp.h"
 #endif
 
+#ifndef CATACOMB_QDPARSE_H
+#  include "qdparse.h"
+#endif
+
 /*----- Data structures ---------------------------------------------------*/
 
 typedef struct field {
   const struct field_ops *ops;		/* Field operations */
   mp *zero, *one;			/* Identities in the field */
+  mp *m;				/* Modulus (prime and binary) */
+  unsigned long nbits;			/* Length of field element in bits */
+  size_t noctets;			/* Length of element in octets */
 } field;
 
+enum {
+  FTY_PRIME,
+  FTY_BINARY
+};
+
 typedef struct field_ops {
 
+  /* --- General information --- */
+
+  unsigned ty;				/* What kind of field this is */
+  const char *name;			/* Human-readable name string */
+
   /* --- Universal operations --- */
 
   void (*destroy)(field */*f*/);
+  mp *(*rand)(field */*f*/, mp */*d*/, grand */*r*/);
+  int (*samep)(field */*f*/, field */*g*/);
 
   mp *(*in)(field */*f*/, mp */*d*/, mp */*x*/);
   mp *(*out)(field */*f*/, mp */*d*/, mp */*x*/);
@@ -102,7 +144,12 @@ typedef struct field_ops {
 
 } field_ops;
 
+#define F_TYPE(f)		(f)->ops->ty
+#define F_NAME(f)		(f)->ops->name
+
 #define F_DESTROY(f)		(f)->ops->destroy((f))
+#define F_RAND(f, d, r)		(f)->ops->rand((f), (d), (r))
+#define F_SAMEP(f, g)		(f)->ops->samep((f), (g))
 
 #define F_IN(f, d, x)		(f)->ops->in((f), (d), (x))
 #define F_OUT(f, d, x)		(f)->ops->out((f), (d), (x))
@@ -140,6 +187,31 @@ typedef struct field_ops {
 
 extern mp *field_id(field */*f*/, mp */*d*/, mp */*x*/);
 
+/* --- @field_samep@ --- *
+ *
+ * Arguments:	@field *f, *g@ = two fields
+ *
+ * Returns:	Nonzero if the fields are identical (not just isomorphic).
+ *
+ * Use:		Checks for sameness of fields.  This function does the full
+ *		check, not just the field-type-specific check done by the
+ *		@sampep@ field operation.
+ */
+
+extern int field_samep(field */*f*/, field */*g*/);
+
+/* --- @field_stdsamep@ --- *
+ *
+ * Arguments:	@field *f, *g@ = two fields
+ *
+ * Returns:	Nonzero if the fields are identical (not just isomorphic).
+ *
+ * Use:		Standard sameness check, based on equality of the @m@
+ *		member.
+ */
+
+extern int field_stdsamep(field */*f*/, field */*g*/);
+
 /*----- Creating fields ---------------------------------------------------*/
 
 /* --- @field_prime@ --- *
@@ -154,6 +226,18 @@ extern mp *field_id(field */*f*/, mp */*d*/, mp */*x*/);
 
 extern field *field_prime(mp */*p*/);
 
+/* --- @field_niceprime@ --- *
+ *
+ * Arguments:	@mp *p@ = the characteristic of the field
+ *
+ * Returns:	A pointer to the field.
+ *
+ * Use:		Creates a field structure for a prime field of size %$p$%,
+ *		using efficient reduction for nice primes.
+ */
+
+extern field *field_niceprime(mp */*p*/);
+
 /* --- @field_binpoly@ --- *
  *
  * Arguments:	@mp *p@ = an irreducible polynomial over %$\gf{2}$%
@@ -166,6 +250,21 @@ extern field *field_prime(mp */*p*/);
 
 extern field *field_binpoly(mp */*p*/);
 
+/* --- @field_parse@ --- *
+ *
+ * Arguments:	@qd_parse *qd@ = parser context
+ *
+ * Returns:	Field pointer if OK, or null.
+ *
+ * Use:		Parses a field description, which has the form
+ *
+ *		  * `prime', `niceprime' or `binpoly'
+ *		  * an optional `:'
+ *		  * the field modulus
+ */
+
+extern field *field_parse(qd_parse */*qd*/);
+
 /*----- That's all, folks -------------------------------------------------*/
 
 #ifdef __cplusplus